In a refrigeration or air conditioning system there is an optimum refrigerant charge for each temperature differential between the conditioned space and ambient. When the system is a reversible heat pump system, however, the volume of the liquid and vapor portions of the system can be quite different in the heating and cooling modes. Thus, while a compromise refrigerant charge can be made based upon the anticipated range and duration of ambient temperatures, the degree of compromise can be exacerbated by the different phase volumes in the different modes. The use of a compromised charge causes a decrease in the heating coefficient of performance and excessive temperatures in the cooling mode. To overcome these losses, a receiver is sometimes employed to effectively change the amount of charge in the system. Since a single receiver or receiver connection is used, in the heating mode, the receiver fills with liquid refrigerant which is thereby effectively removed from the circulating system. Similarly, in the cooling mode, the receiver fills with gaseous refrigerant which is thereby effectively removed from the circulating system. Because liquid refrigerant is effectively removed from the system in the heating mode and gaseous refrigerant is effectively removed from the system in the cooling mode, the effective mass of the refrigerant is different for each mode of operation, but the mass removal from cooling mode is not significant.